Sprinkle flour onto a clean work surface. Lay out the puff pastry sheets next to each other and sprinkle more flour onto a rolling pin. Roll out the pastry, connecting the 2 sheets, until you have a 20x15-inch (50x30-cm) rectangle about ⅛-inch (3 mm) thick.
Use a pizza cutter or sharp knife to cut the puff pastry into 32 even squares.
Dollop a teaspoon of marinara sauce on top of each pastry square.
Place a pre-cooked meatball in the middle of each square.
Wrap the puff pastry dough around each meatball to form balls.
Preheat the oven to 350°F (180°C).
In a medium bowl, combine the butter, garlic, and parsley.
Place half of the pastry meatballs into a bundt pan.
Brush the tops of the balls with garlic butter and sprinkle with half of the mozzarella cheese. Add the rest of the meatballs on top, brush with garlic butter, and finish with the rest of the cheese. Reserve the remaining garlic butter.
Bake for 40 minutes.
Brush the balls at the top of the pan with garlic butter, then invert the meatball ring onto a wire rack-lined baking sheet.
Brush the top of the ring with more garlic butter.
Sprinkle mozzarella on top of the ring.
Bake for another 20 minutes until pastry is lightly golden brown.
Brush the surface of the ring with leftover butter mixture.
Transfer to a serving platter and place a small bowl of marinara sauce in the middle of the monkey bread.